docs: def cli(env, columns):
      """List Users."""
  
      mgr = SoftLayer.UserManager(env.client)
      users = mgr.list_users()
  
      table = formatting.Table(columns.columns)
      for user in users:
          table.add_row([value or formatting.blank()
                         for value in columns.row(user)])
  
      env.fout(table)